Tetra-aryl indacenodithiophene-based polycyclic polymers and their use

ABSTRACT

The present invention relates to compounds comprising a tetra-aryl indacenodithiophene-based structural unit, the synthesis of such compounds as well as their use in organic electronic devices. The invention further relates to organic electronic devices comprising such compounds.

TECHNICAL FIELD

The present invention relates to compounds comprising a tetra-aryl indacenodithiophene-based structural unit, the synthesis of such compounds as well as their use in organic electronic devices. The invention further relates to organic electronic devices comprising such compounds.

BACKGROUND AND DESCRIPTION OF THE PRIOR ART

In recent years, major efforts have been made to develop organic semiconducting (OSC) materials in order to be able to produce more versatile, lower cost electronic devices. Such materials find application in a wide range of devices or apparatus, such as for example organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), photodetectors, organic photovoltaic (OPV) cells, sensors, memory elements and logic circuits to name a few only. The organic semiconducting materials are generally present in the electronic device in the form of a thin layer of, for example, between 50 and 300 nm thickness.

Polycyclic aromatic compounds, either as “small molecules”, such as for example pentacene, or in form of polymers, such as for example poly(hexylthiophene), are widely used in organic electronics because of their good semiconducting properties, However, these materials have a number of disadvantages, which hinder large-scale commercial production. In general these polycyclic aromatic compounds are characterized by low solubility and in consequence can often be processed by vapor deposition methods only. Furthermore they are also difficult to synthesize and in some cases, such as for example pentacene, extremely sensitive to oxidation. On top of this, their charge-carrier mobility and on/off ratio still leave room for improvement.

A promising class of conjugated polymers is based on the indenofluorene unit and was first reported in S. Setayesh et al., Macromolecules 2000, 33, 2016-2020 (DOI: 10.1021/ma9914366) as a candidate material for blue light emission in electroluminescent applications. Indenofluorene copolymers have also been disclosed in WO 2007/131582 for application as organic semiconducting material in transistor devices.

Polymers comprising indacenodithiophene units have been disclosed for example in WO 2012/174561; in WO 2012/088698; in EP 2 075 274 A1; in W. Wen et al., Chem. Commun., 2013, 49, 7192 (DOI: 10.1039/c3cc43229g); in C. Y. Yu et al., Chem. Mater. 2009, 21, 3262-3269 (DOI: 10.1021/cm9007798); in C. P. Chen et al., J. Am. Chem. Soc. 2008, 130, 12828-12833; in Y. Sun et al., J. Mater. Chem., 2011, 21, 13247 (DOI: 10.1039/c1jm11564b); in J. H. Tsai et al., Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 48, 2351-2360 (2010) (DOI: 10.1002/pola.24002); in Y. Zhang et al., Macromolecules 2011, 44, 4752-4758 (DOI: 10.1021/ma2008699); in S. H. Chan et al., Macromolecules 2008, 41, 5519-5526 (DOI: 10.1021/ma800494k); in I. McCulloch et al., Nature Materials, vol. 5, April 2006, pages 328-333 (DOI: 10.1038/nmat1612); and in Y. C. Chen et al., J. Sol. Energy Eng. 132(2), 021103 (May 3, 2010) (DOI: 10.1115/1.4001150).

However, the reported charge-carrier mobilities reach at best 0.2 cm²/Vs while most of the reported values are well below 0.1 cm²/Vs.

It is therefore an objective of the present invention to provide new organic semiconducting materials for use in electronic devices. Preferably, such new organic semiconducting materials are characterized by advantageous properties in one or more of good processability, high charge-carrier mobility, high on/off ratio, good oxidative stability and long lifetime in electronic devices. Additionally, it is an objective of the present invention to extend the pool of semiconducting materials available to the expert. Other objectives of the present application are immediately evident to the expert from the following detailed description and examples

SUMMARY OF THE INVENTION

The present inventors have now surprisingly found that the above objectives may be attained either individually or in any combination by the compound of the present application.

The present application therefore provides for a compound comprising at least one constitutional unit M selected from the group consisting of formula (I-a) and formula (I-b)

wherein

-   X¹ and X² are independently of each other S or Se; -   Ar¹, Ar², Ar³ and Ar⁴ are independently of each other aryl     comprising at least one substituent group R, said substituent group     R being an organyl or organoheteryl comprising from 13 to 19 carbon     atoms; -   a is 0 or an integer from 1 to 10; and -   Ar⁵ is at each occurrence independently selected from the group     consisting of aryl, substituted aryl, heteroaryl and substituted     heteroaryl having up to 30 aromatic ring atoms.

The present application also provides for a blend or mixture comprising said compound and one or more compounds selected from the group consisting of binders and compounds or polymers having semiconducting, charge transport, charge blocking, photoconducting or light emitting properties.

Further, the present application provides for a formulation comprising said compound and at least one organic solvent.

In addition, the present application provides for a material or layer comprised in an electronic device, said material or layer comprising the compound of the present application and said material or layer having charge transport, semiconducting, electrically conducting, photoconducting or light emitting properties.

Furthermore, the present application provides for an electronic device comprising the compound of the present application.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 shows the transfer characteristics and the charge carrier mobility of the top-gate organic field-effect transistor (OFET) of Example 4 prepared using Polymer 2.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the present application an asterisk (“*”) denotes a linkage to an adjacent unit or group or, in case of a polymer, to an adjacent repeating unit or any other group, such as for example a terminal group or an endcap group.

In the present application the term “arylene” is used to denote a bivalent group derived from an arene by removal of a hydrogen atom from two ring carbon atoms (International Union of Pure and Applied Chemistry, Compendium of Chemical Technology, Gold Book, Version 2.3.2, 2012-08-19, page 115). In the present application the term “heteroarylene” is used correspondingly to denote bivalent groups derived from a heteroarene by removal of a hydrogen from two ring carbon atoms.

As used herein, the term “conjugated” will be understood to mean a compound (for example a polymer) that contains mainly C atoms with sp²-hybridisation (or optionally also sp-hybridization), and wherein these C atoms may also be replaced by hetero atoms. In the simplest case this is for example a compound with alternating C—C single and double (or triple) bonds, but is also inclusive of compounds with aromatic units like for example 1,4-phenylene. The term “mainly” in this connection will be understood to mean that a compound with naturally (spontaneously) occurring defects, or with defects included by design, which may lead to interruption of the conjugation, is still regarded as a conjugated compound. See also International Union of Pure and Applied Chemistry, Compendium of Chemical Technology, Gold Book, Version 2.3.2, 19. August 2012, pages 322-323.

As used herein, unless stated otherwise the molecular weight is given as the number average molecular weight M_(n) or weight average molecular weight M_(w), which is determined by gel permeation chromatography (GPC) against polystyrene standards in eluent solvents such as tetrahydrofuran, trichloromethane (TCM, chloroform), chlorobenzene or 1,2,4-trichlorobenzene. Unless stated otherwise, chlorobenzene is used as solvent. The molecular weight distribution (“MWD”), which may also be referred to as polydispersity index (“PDI”), of a polymer is defined as the ratio M_(w)/M_(n). The degree of polymerization, also referred to as total number of repeat units, m, will be understood to mean the number average degree of polymerization given as m=M_(n)/M_(u), wherein M_(n) is the number average molecular weight of the polymer and M_(u) is the molecular weight of the single repeat unit; see J. M. G. Cowie, Polymers: Chemistry & Physics of Modern Materials, Blackie, Glasgow, 1991.

As used herein, the term “organyl” or “organyl group” is to denote any organic substituent group, regardless of functional type, having one or more free valence at a carbon atom (see also International Union of Pure and Applied Chemistry, Compendium of Chemical Technology, Gold Book, Version 2.3.2, 2012-08-09, page 1040).

As used herein, the term “organoheteryl” or “organoheteryl group” is used to denote any univalent or polyvalent groups comprising carbon, which are thus organic, but which have their free valence at an atom other than carbon (see also International Union of Pure and Applied Chemistry, Compendium of Chemical Technology, Gold Book, Version 2.3.2, 2012-08-09, page 1038).

As used herein, the term “hetero atom” will be understood to mean an atom in an organic compound that is not a H- or C-atom, and preferably will be understood to mean N, O, S, P, Si, Se, As, Te or Ge, unless specified otherwise.

An organyl or organoheteryl group comprising a chain of 3 or more C atoms may be straight-chain, branched and/or cyclic, including spiro and/or fused rings.

Preferred organyl and organoheteryl groups include alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy, each of which is optionally substituted and has 1 to 40, preferably 1 to 25, very preferably 1 to 18 C atoms, furthermore optionally substituted aryl or aryloxy having 6 to 40, preferably 6 to 25 C atoms, furthermore alkylaryloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy, each of which is optionally substituted and has 6 to 40, preferably 7 to 40 C atoms, wherein all these groups do optionally contain one or more hetero atoms, preferably selected from N, O, S, P, Si, Se, As, Te and Ge, unless specified otherwise.

The organyl or organoheteryl group may be a saturated or unsaturated acyclic group, or a saturated or unsaturated cyclic group. Unsaturated acyclic or cyclic groups are preferred, especially aryl, alkenyl and alkynyl groups (especially ethynyl). Where the C₁-C₄₀ organyl or organoheteryl group is acyclic, the group may be straight-chain or branched. Examples of organyl or organoheteryl groups include for example: a C₁-C₄₀ alkyl group, a C₁-C₄₀ fluoroalkyl group, a C₁-C₄₀ alkoxy or oxaalkyl group, a C₂-C₄₀ alkenyl group, a C₂-C₄₀ alkynyl group, a C₃-C₄₀ allyl group, a C₄-C₄₀ alkyldienyl group, a C₄-C₄₀ polyenyl group, a C₂-C₄₀ ketone group, a C₂-C₄₀ ester group, a C₆-C₁₈ aryl group, a C₆-C₄₀ alkylaryl group, a C₆-C₄₀ arylalkyl group, a C₄-C₄₀ cycloalkyl group, a C₄-C₄₀ cycloalkenyl group, and the like. Preferred among the foregoing groups are a C₁-C₂₀ alkyl group, a C₁-C₂₀ fluoroalkyl group, a C₂-C₂₀ alkenyl group, a C₂-C₂₀ alkynyl group, a C₃-C₂₀ allyl group, a C₄-C₂₀ alkyldienyl group, a C₂-C₂₀ ketone group, a C₂-C₂₀ ester group, a C₆-C₁₂ aryl group, and a C₄-C₂₀ polyenyl group, respectively. Also included are combinations of groups having carbon atoms and groups having hetero atoms, like e.g. an alkynyl group, preferably ethynyl, that is substituted with a silyl group, preferably a trialkylsilyl group.

The terms “aryl” and “heteroaryl” as used herein preferably mean a mono-, bi- or tricyclic aromatic or heteroaromatic group with 4 to 30 ring C atoms that may also comprise condensed rings and is optionally substituted with one or more groups L, wherein L is selected from halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR⁰R⁰⁰, —C(═O)X⁰, —C(═O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —CF₃, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, or organyl or organoheteryl with 1 to 40 C atoms that optionally comprises one or more hetero atoms, and is preferably alkyl, alkoxy, thiaalkyl, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy with 1 to 20 C atoms that is optionally fluorinated, and R⁰, R⁰⁰, R⁰⁰⁰ and X⁰ are as defined below. Very preferred substituents L are selected from halogen, most preferably F, or alkyl, alkoxy, oxaalkyl, thioalkyl, fluoroalkyl and fluoroalkoxy with 1 to 12 C atoms or alkenyl, and alkynyl with 2 to 12 C atoms.

Especially preferred aryl and heteroaryl groups are phenyl, phenyl wherein one or more CH groups are replaced by N, naphthalene, thiophene, selenophene, thienothiophene, dithienothiophene, fluorene and oxazole, all of which can be unsubstituted, mono- or polysubstituted with L as defined above. Very preferred rings are selected from pyrrole, preferably N-pyrrole, furan, pyridine, preferably 2- or 3-pyridine, pyrimidine, pyridazine, pyrazine, triazole, tetrazole, pyrazole, imidazole, isothiazole, thiazole, thiadiazole, isoxazole, oxazole, oxadiazole, thiophene, preferably 2-thiophene, selenophene, preferably 2-selenophene, thieno[3,2-b]thiophene, thieno[2,3-b]thiophene, furo[3,2-b]furan, furo[2,3-b]furan, seleno[3,2-b]selenophene, seleno[2,3-b]selenophene, thieno[3,2-b]selenophene, thieno[3,2-b]furan, indole, isoindole, benzo[b]furan, benzo[b]thiophene, benzo[1,2-b;4,5-b′]dithiophene, benzo[2,1-b;3,4-b′]dithiophene, quinole, 2-methylquinole, isoquinole, quinoxaline, quinazoline, benzotriazole, benzimidazole, benzothiazole, benzisothiazole, benzisoxazole, benzoxadiazole, benzoxazole, benzothiadiazole, all of which can be unsubstituted, mono- or polysubstituted with L as defined above. Further examples of aryl and heteroaryl groups are those selected from the groups shown hereinafter.

An alkyl or alkoxy radical, i.e. where the terminal CH₂ group is replaced by —O—, can be straight-chain or branched. It is preferably straight-chain (or linear). Suitable examples of such alkyl and alkoxy radical are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy, tetradecoxy, pentadecoxy, hexadecoxy, heptadecoxy or octadecoxy. Preferred alkyl and alkoxy radicals have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16 or 18 carbon atoms. More preferred alkyl and alkoxy radicals have 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Suitable examples of such preferred alkyl and alkoxy radicals may be selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy and decoxy.

An alkenyl group, wherein one or more CH₂ groups are replaced by —CH═CH— can be straight-chain or branched. It is preferably straight-chain, has 2 to 10 C atoms and accordingly is preferably vinyl, prop-1-enyl, or prop-2-enyl, but-1-enyl, but-2-enyl or but-3-enyl, pent-1-enyl, pent-2-enyl, pent-3-enyl or pent-4-enyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl, hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl or hept-6-enyl, oct-1-enyl, oct-2-enyl, oct-3-enyl, oct-4-enyl, oct-5-enyl, oct-6-enyl or oct-7-enyl, non-1-enyl, non-2-enyl, non-3-enyl, non-4-enyl, non-5-enyl, non-6-enyl, non-7-enyl or non-8-enyl, dec-1-enyl, dec-2-enyl, dec-3-enyl, dec-4-enyl, dec-5-enyl, dec-6-enyl, dec-7-enyl, dec-8-enyl or dec-9-enyl.

Especially preferred alkenyl groups are C₂-C₇-1E-alkenyl, C₄-C₇-3E-alkenyl, C₅-C₇-4-alkenyl, C₆-C₇-5-alkenyl and C₇-6-alkenyl, in particular C₂-C₇-1E-alkenyl, C₄-C₇-3E-alkenyl and C₅-C₇-4-alkenyl. Examples for particularly preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Alkenyl groups having up to 5 C atoms are generally preferred.

An oxaalkyl group, i.e. where one CH₂ group is replaced by —O—, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, for example. Oxaalkyl, i.e. where one CH₂ group is replaced by —O—, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, for example.

In an alkyl group wherein one CH₂ group is replaced by —O— and one by —C(O)—, these radicals are preferably neighboured. Accordingly these radicals together form a carbonyloxy group —C(O)—O— or an oxycarbonyl group —O—C(O)—. Preferably this group is straight-chain and has 2 to 6 C atoms. It is accordingly preferably selected from the group consisting of acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetyloxypropyl, 3-propionyloxypropyl, 4-acetyloxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)propyl, and 4-(methoxycarbonyl)-butyl.

An alkyl group wherein two or more CH₂ groups are replaced by —O— and/or —C(O)O— can be straight-chain or branched. It is preferably straight-chain and has 3 to 12 C atoms. Accordingly it is preferably selected from the group consisting of bis-carboxy-methyl, 2,2-bis-carboxy-ethyl, 3,3-bis-carboxy-propyl, 4,4-bis-carboxy-butyl, 5,5-bis-carboxy-pentyl, 6,6-bis-carboxy-hexyl, 7,7-bis-carboxy-heptyl, 8,8-bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy-decyl, bis-(methoxycarbonyl)-methyl, 2,2-bis-(methoxycarbonyl)-ethyl, 3,3-bis-(methoxycarbonyl)-propyl, 4,4-bis-(methoxycarbonyl)-butyl, 5,5-bis-(methoxycarbonyl)-pentyl, 6,6-bis-(methoxycarbonyl)-hexyl, 7,7-bis-(methoxycarbonyl)-heptyl, 8,8-bis-(methoxycarbonyl)-octyl, bis-(ethoxycarbonyl)-methyl, 2,2-bis-(ethoxycarbonyl)-ethyl, 3,3-bis-(ethoxycarbonyl)-propyl, 4,4-bis-(ethoxycarbonyl)-butyl, and 5,5-bis-(ethoxycarbonyl)-hexyl.

A thioalkyl group, i.e where one CH₂ group is replaced by —S—, is preferably straight-chain thiomethyl (—SCH₃), 1-thioethyl (—SCH₂CH₃), 1-thiopropyl (=—SCH₂CH₂CH₃), 1-(thiobutyl), 1-(thiopentyl), 1-(thiohexyl), 1-(thioheptyl), 1-(thiooctyl), 1-(thiononyl), 1-(thiodecyl), 1-(thioundecyl) or 1-(thiododecyl), wherein preferably the CH₂ group adjacent to the sp² hybridised vinyl carbon atom is replaced.

A fluoroalkyl group is preferably perfluoroalkyl C_(i)F_(2i+1), wherein i is an integer from 1 to 15, in particular CF₃, C₂F₅, C₃F₇, C₄F₉, C₅F₁₁, C₆F₁₃, C₇F₁₅ or C₈F₁₇, very preferably C₆F₁₃, or partially fluorinated alkyl, in particular 1,1-difluoroalkyl, all of which are straight-chain or branched.

Alkyl, alkoxy, alkenyl, oxaalkyl, thioalkyl, carbonyl and carbonyloxy groups can be achiral or chiral groups. Particularly preferred chiral groups are 2-butyl (=1-methylpropyl), 2-methylbutyl, 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, in particular 2-methylbutyl, 2-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethyl-hexoxy, 1-methylhexoxy, 2-octyloxy, 2-oxa-3-methylbutyl, 3-oxa-4-methyl-pentyl, 4-methylhexyl, 2-butyloctyl, 2-hexyldecyl, 2-octyldodecyl, 7-decylnonadecyl, 2-hexyl, 2-octyl, 2-nonyl, 2-decyl, 2-dodecyl, 6-meth-oxyoctoxy, 6-methyloctoxy, 6-methyloctanoyloxy, 5-methylheptyloxy-carbonyl, 2-methylbutyryloxy, 3-methylvaleroyloxy, 4-methylhexanoyloxy, 2-chloropropionyloxy, 2-chloro-3-methylbutyryloxy, 2-chloro-4-methyl-valeryl-oxy, 2-chloro-3-methylvaleryloxy, 2-methyl-3-oxapentyl, 2-methyl-3-oxa-hexyl, 1-methoxypropyl-2-oxy, 1-ethoxypropyl-2-oxy, 1-propoxypropyl-2-oxy, 1-butoxypropyl-2-oxy, 2-fluorooctyloxy, 2-fluorodecyloxy, 1,1,1-trifluoro-2-octyloxy, 1,1,1-trifluoro-2-octyl, 2-fluoromethyloctyloxy for example. Very preferred are 2-hexyl, 2-octyl, 2-octyloxy, 1,1,1-trifluoro-2-hexyl, 1,1,1-trifluoro-2-octyl and 1,1,1-trifluoro-2-octyloxy.

Preferred achiral branched groups are isopropyl, isobutyl (=methylpropyl), isopentyl (=3-methylbutyl), tert. butyl, isopropoxy, 2-methyl-propoxy and 3-methylbutoxy.

In a preferred embodiment, the organyl groups are independently of each other selected from primary, secondary or tertiary alkyl or alkoxy with 1 to 30 C atoms, wherein one or more H atoms are optionally replaced by F, or aryl, aryloxy, heteroaryl or heteroaryloxy that is optionally alkylated or alkoxylated and has 4 to 30 ring atoms. Very preferred groups of this type are selected from the group consisting of the following formulae

wherein “ALK” denotes optionally fluorinated, preferably linear, alkyl or alkoxy with 1 to 20, preferably 1 to 12 C-atoms, in case of tertiary groups very preferably 1 to 9 C atoms, and the dashed line denotes the link to the ring to which these groups are attached. Especially preferred among these groups are those wherein all ALK subgroups are identical.

—CY¹═CY²— is preferably —CH═CH—, —CF═CF— or —CH═C(CN)—.

As used herein, “halogen” includes F, Cl, Br or I, preferably F, Cl or Br.

As used herein, —CO—, —C(═O)— and —C(O)— will be understood to mean a carbonyl group, i.e. a group having the structure

R⁰, R⁰⁰ and R⁰⁰⁰ are at each occurrence independently of each other selected from the group consisting of H, F, C₁₋₄₀ organyl or organoheteryl and substituted C₁₋₄₀ organyl or organoheteryl. Preferably, R⁰, R⁰⁰ and R⁰⁰⁰ are at each occurrence independently of each other selected from the group consisting of H, F, alkyl having from 1 to 20, preferably from 1 to 10, carbon atoms, phenyl, phenyl wherein one or more hydrogen are replaced by fluorine and alkyl having from 1 to 20, preferably from 1 to 10, carbon atoms wherein one or more hydrogen is replaced by fluorine. Examples of alkyls that are suitable for R⁰, R⁰⁰ and R⁰⁰⁰ are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl (or “t-butyl”), pentyl, hexyl, heptyl, octyl, nonyl and decyl.

X⁰ is used to denote halogen, preferably F, Cl or Br.

Constitutional Unit M

The present inventors have after intensive experimentation found that the properties of an indacenodithiophene compound can be drastically improved by properly selecting the substituents on the indacenodithiophene unit.

The compound of the present invention therefore comprises at least one constitutional (or structural) unit M selected from the group consisting of formula (I-a) and formula (I-b)

wherein X¹, X², Ar¹, Ar², Ar³, Ar⁴, Ar⁵ and a are as defined in the following.

Preferably, the compound of the present invention comprises at least one constitutional unit M of formula (I-a).

X¹ and X² are independently of each other S or Se. Preferably, X¹ and X² are both S.

Ar¹, Ar², Ar³ and Ar⁴ are independently of each other aryl comprising at least one substituent group R with R as defined in the following. Preferably said aryl is substituted with a substituent group R, i.e. with one substituent group R only.

Preferred Ar¹, Ar², Ar³ and Ar⁴ are independently of each other selected from the group consisting of formulae (F1) to (F9). Most preferably Ar¹, Ar², Ar³ and Ar⁴ are independently of each other selected from formula (F1).

wherein R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ are independently of each other selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms and substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te or Ge, with N, O and S being preferred heteroatoms, with X⁰, R⁰, R⁰⁰ and R⁰⁰⁰ as defined above, provided that at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R as defined herein. Preferably R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ are independently of each other selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —OCN, —C(O)R⁰, —NR⁰R⁰⁰, —SR⁰, —OR⁰, —SiR⁰R⁰⁰R⁰⁰⁰, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰, R⁰⁰ and R⁰⁰⁰ as defined above, provided that at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R as defined herein. More preferably, R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ are independently of each other selected from the group consisting of H, F, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰ as defined above, provided that at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R as defined herein. Even more preferably, at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R as defined herein, the others being H. Most preferably, one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R as defined herein with the others being H.

A preferred example of phenyl suitable for Ar¹, Ar², Ar³ and Ar⁴ is

with R as defined in the following.

Group R is an organyl or organoheteryl comprising from 13 to 19 carbon atoms. Preferably R is an alkyl having from 13 to 19 carbon atoms (e.g. having 13, 14, 15, 16, 17, 18 or 19 carbon atoms). Said alkyl having from 13 to 19 carbon atoms may be a linear alkyl or a branched alkyl. As exemplary such alkyl mention may be made of liner C₁₆H₃₃.

It is noted that if two or more of Ar¹, Ar², Ar³ and Ar⁴ are one or more of any of formulae (F1) to (F9) then these may also differ from each other in terms of the respective groups R²¹ to R²⁹.

The tetra-aryl indacenodithiophene may be synthesized using standard reactions. An exemplary synthesis is shown in Scheme 1, wherein O—R′ is used to denote a leaving group, such as for example methoxy or ethoxy, and for reasons of simplicity Ar is used to denote Ar¹, Ar², Ar³ and Ar⁴, respectively.

a is 0 or an integer of from 1 to 10 (i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10). Preferably a is an integer of from 1 to 10. More preferably a is an integer of from 1 to 6. Most preferably a is an integer of from 1 to 3.

Ar⁵ is at each occurrence independently selected from the group consisting of —CR¹═CR¹—, —C≡C—, arylene having from 6 to 30 aromatic carbon atoms and heteroarylene having from 5 to 30 aromatic ring atoms, wherein said arylene or heteroarylene may be unsubstituted or substituted with one or more groups R². Preferred heteroarylenes suitable for Ar⁵ comprise one or more heteroatoms selected from the group consisting of O, S, Se, N and N—R⁰, with O, S, N and N—R⁰ being preferred.

R¹ is at each occurrence independently selected from the group consisting of F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms and substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te or Ge, with N, O and S being preferred heteroatoms, with X⁰, R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Preferably R¹ is at each occurrence independently selected from the group consisting of F, Br, Cl, —CN, —NC, —NCO, —OCN, —C(O)R⁰, —NR⁰R⁰⁰, —SR⁰, —OR⁰, —SiR⁰R⁰⁰R⁰⁰⁰, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Most preferably, R¹ is at each occurrence independently selected from the group consisting of F, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰ as defined above.

R² is at each occurrence independently selected from the group consisting of F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms and substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te or Ge, with N, O and S being preferred heteroatoms, with X⁰, R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Preferably R² is at each occurrence independently selected from the group consisting of F, Br, Cl, —CN, —NC, —NCO, —OCN, —C(O)R⁰, —NR⁰R⁰⁰, —SR⁰, —OR⁰, —SiR⁰R⁰⁰R⁰⁰⁰, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Most preferably, R² is at each occurrence independently selected from the group consisting of F, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰ as defined above.

Preferably Ar⁵ may be selected from the group consisting of arylene or heteroarylene having electron donor properties and arylene or heteroarylene having electron acceptor properties.

Preferred examples of Ar⁵ may be selected from the group consisting of formulae (A1) to (A96) and (D1) to (D140).

Suitable examples of aryl and heteroaryl with electron donor properties may be selected from the group consisting of the following formulae (D1) to (D140)

wherein R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷ and R¹⁸ are independently selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR, —NO₂, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms and substituted or unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te or Ge, with N, O and S being preferred heteroatoms, with X⁰, R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Preferably R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷ and R¹⁸ are independently selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —OCN, —C(O)R⁰, —NR⁰R⁰⁰, —SR⁰, —OR⁰, —SiR⁰R⁰⁰R⁰⁰⁰, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰, R⁰⁰ and R⁰⁰⁰ as defined above. Most preferably, R¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷ and R¹⁸ are independently selected from the group consisting of H, F, phenyl, phenyl substituted with one or more R⁰, alkyl having from 1 to 20 carbon atoms and alkyl having from 1 to 20 carbon atoms wherein one or more hydrogen is replaced by fluorine, with R⁰ as defined above.

Suitable examples of aryl and heteroaryl with electron acceptor properties may be selected from the group consisting of the following formula (A1) to (A96)

wherein R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are as defined above in respect to (D1) to (D140).

Compounds comprising the structural unit of formulae (I-a) or (I-b) as defined above may preferably be selected from the group consisting of small molecules, monomers and polymers. As used herein, the term “small molecule” will be used to denote a compound comprising a structural unit of formula (I-a) or (I-b) and two inert chemical groups, which are inert under use condition and thus inhibit such a small molecule from being polymerized. In contrast hereto, the term “monomer” is used to denote a compound comprising a structural unit of formula (I-a) or (I-b) and at least one reactive chemical group, which allows such monomer to be reacted so as to form part of a polymer.

Small Molecule and Monomer

In one aspect the present application provides for a small molecule, i.e. for a compound comprising a structural unit of formula (I-a) or (I-b) and two inert chemical groups R^(a) and R^(b). Such a small molecule may for example be represented by formula (IV-a) R^(a)-M⁰-R^(b)  (IV-a) wherein M⁰ comprises a structural unit M of formula (I-a) or (I-b) and R^(a) and R^(b) are inert chemical groups. Such inert chemical groups R^(a) and R^(b) may independently of each other for example be chosen from the group consisting of hydrogen, fluorine, alkyl having from 1 to 10 carbon atoms, fluoroalkyl having from 1 to 10 carbon atoms, aromatic ring systems of from 5 to 30 carbon atoms and aromatic ring systems of from 5 to 30 carbon atoms wherein one or more hydrogen atom may independently of each other be replaced by fluorine or alkyl having from 1 to 10 carbon atoms.

In another aspect the present application provides for a monomer, i.e. for a compound comprising a structural unit of formula (I-a) or (I-b) and at least one reactive chemical group R^(c) which may be selected from the group consisting of Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, —SiMe₂F, —SiMeF₂, —O—SO₂Z¹, —B(OZ²)₂, —CZ³═C(Z³)₂, —C≡CH, —C≡CSi(Z¹)₃, —ZnX⁰ and —Sn(Z⁴)₃, preferably —B(OZ²)₂ or —Sn(Z⁴)₃, wherein X⁰ is as defined above, and Z¹, Z², Z³ and Z⁴ are selected from the group consisting of alkyl and aryl, preferably alkyl having from 1 to 10 carbon atoms, each being optionally substituted with R⁰ as defined above, and two groups Z² may also together form a cyclic group. Alternatively such a monomer may comprise two reactive chemical groups and is for example represented by formula (IV-b) R^(c)-M⁰-R^(d)  (IV-b) wherein M⁰ comprises a structural M unit of formula (I-a) or (I-b) and R^(c) and R^(d) are reactive chemical groups as defined above for R^(c).

Preferably, M⁰ in formulae (IV-a) and (IV-b) may further comprise one or more (for example 2, 3, 4, 5, 6, 7, 8, 9 or 10) aryl or heteroaryl as defined above. Preferred examples of M⁰ may comprise, preferably consist of, the following *—U^(a) _(m1)—Ar^(a) _(m2)—U^(b) _(m3)—Ar^(b) _(m4)—Ar^(c) _(m5)—*  (V) wherein

-   U^(a) and U^(b) are independently of each other selected from the     structural unit M of formula (I-a), (I-b) and any of its subformulae     as defined above; -   Ar^(a), Ar^(b) and Ar^(c) are independently of each other aryl or     heteroaryl different from U^(a) and U^(b); -   m1, m2, m3 and m4 are independently of each other selected from the     group consisting of 0, 1 and 2, with the provision that at least one     of m1 and m3 is not 0; and -   m5 is 0 or an integer from 1 to 10 (for example 2, 3, 4, 5, 6, 7, 8     or 9).

Preferably Ar^(a), Ar^(b) and Ar^(c) are selected from aryl having from 5 to 30 ring atoms and heteroaryl having from 5 to 30 ring atoms. Said aryl and heteroaryl may optionally be substituted with at least one substituent R⁰ as defined earlier. With respect to Ar^(a), Ar^(b) and Ar^(c) preferred substituents R⁰ are selected from alkyl having from 1 to 20 carbon atoms, more preferably from alkyl having from 1 to 10 carbon atoms. Optionally, said alkyl may be partially or completely fluorinated.

Preferred small molecules and monomers are those with M⁰ selected from one of the following formula (V-a-1) and (V-a-2) *—Ar^(a) _(m2)—U^(b)—Ar^(b) _(m4)—*  (V-a-1) *—U^(a) _(m1)—Ar^(a) _(m2)—U^(b) _(m3)—*  (V-a-2) with Ar^(a), Ar^(b), U^(a), U^(b), m1, m2, m3 and m4 as defined above.

Especially preferred small molecules and monomers are those with M⁰ selected from one of the following formulae (V-b-1) to (V-b-5) *—Ar^(a)—U^(a)—Ar^(b)—*  (V-b-1) *—U^(a)—*  (V-b-2) *—Ar^(a)—U^(a)—*  (V-b-3) *—U^(a)—Ar^(b)—*  (V-b-4) *—U^(a)—Ar^(a)—U^(b)—*  (V-b-5) with Ar^(a), Ar^(b), U^(a) and U^(b) as defined above.

Particularly preferred examples of M⁰ of formulae (V), (V-a-1), (V-a-2) and (V-b-1) to (V-b-5) are those wherein one or more of Ar^(a), Ar^(b) and Ar^(c) denote aryl or heteroaryl, preferably having electron donor properties or electron acceptor properties. Preferred examples of Ar^(a), Ar^(b) and Ar^(c) may be selected from the group consisting of formulae (D1) to (D140) and (A1) to (A96).

The monomers of the present invention may be synthesized by generally known reactions, such as for example lithiation followed by reaction with a reagent that supplies the respective functional groups. Examples of such reactions are indicated in Scheme 2.

Polymer

In a further aspect the present application provides for an oligomer or polymer, i.e. for a compound comprising more than one structural unit of formula (I-a) or (I-b). Preferably such oligomer or polymer comprises more than one group M⁰ as defined in any one of formulae (V), (V-a-1), (V-a-2) and (V-b-1) to (V-b-5). At each occurrence M⁰ may be the same or different.

Optionally, such oligomer or polymer may further comprise a repeating unit comprising a group selected from monocyclic or polycyclic aryl or heteroaryl groups that are optionally substituted. Preferably such further repeating units are selected from one of the following *—[—Ar^(d) _(m6)—Ar^(a) _(m2)—Ar^(e) _(m7)—Ar^(b) _(m4)—Ar^(c) _(m5)]—*  (VI) wherein

-   Ar^(a), Ar^(b), Ar^(c), m2, m4 and m5 are as defined above; -   Ar^(d) and Ar^(e) are independently of each aryl or heteroaryl with     electron donor properties or electron acceptor properties,     preferably independently of each other chosen from the group     consisting of formulae (D1) to (D140) and (A1) to (A96); and -   m6 and m7 are independently of each other 0, 1 or 2, provided that     at least one of m6 and m7 is not 0 (for example m6 is 0 and m7 is 1,     or m6 is 1 and m7 is 0, or m6 is 1 and m7 is 1).

Preferred oligomers and polymers may for example comprise a polymer chain of formula (VII)

wherein

-   m is an integer >1; -   M¹, M² and M³ are independently of each other monomeric units as     defined below, provided that at least one of M¹, M² and M³ comprises     a structural unit M of formula (I-a) or (I-b); -   mx is >0 and ≤1; -   my is ≥0 and <1; and -   mz is ≥0 and <1,     with the provision that mx+my+mz=1.

Preferably M¹, M² and M³ are independently of each other selected from the group consisting of M⁰ as defined in and for above formulae (V), (V-a-1), (V-a-2) and (V-b-1) to (V-b-5).

Examples of suitable polymer chains of formula (VI) may be selected from the following formulae (VII-1) to (VII-10) *—[(Ar^(a)—U^(a)—Ar^(b))_(mx)—(Ar^(c))_(my)]_(m)—*  (VII-1) *—[(Ar^(a)—U^(a)—Ar^(b))_(mx)—(Ar^(c)—Ar^(c))_(my)]_(m)—*  (VII-2) *—[(Ar^(a)—U^(a)—Ar^(b))_(mx)—(Ar^(c)—Ar^(c)—Ar^(c))_(my)]_(m)—*  (VII-3) *—[(Ar^(a))_(m2)—(U^(a))_(m1)—(Ar^(b))_(m4)—(Ar^(c))_(m5)]_(m)—*  (VII-4) *—([(Ar^(a))_(m2)—(U^(a))_(m1)—(Ar^(b))_(m4)—(Ar^(c))_(m5)]_(mx)—[(Ar^(a))_(m2)—(Ar^(d))_(m6)—(Ar^(b))_(m4)—(Ar^(c))_(m5)]_(my))_(m)—*  (VII-5) *—[(U^(a)—Ar^(a)—U^(b))_(mx)—(Ar^(b)—Ar^(c))_(my)]_(m)—*  (VII-6) *—[(U^(a)—Ar^(a)—U^(b))_(mx)—(Ar^(b)—Ar^(c)—Ar^(b))_(my)]_(m)—*  (VII-7) *—[(U^(a))_(m1)—(Ar^(a))_(m2)—(U^(b))_(m3)—(Ar^(b))_(m4)]_(m)—*  (VII-8) *—([(U^(a))_(m1)—(Ar^(a))_(m2)—(U^(b))_(m3)—(Ar^(b))_(m4)]_(mx)—[(Ar^(d))_(m6)—(Ar^(a))_(m2)—(Ar^(e))_(m7)—(Ar^(b))_(m4)]_(my))_(m)—*  (VII-9) *—[(U^(a)—Ar^(a))_(mx)—(U^(b)—Ar^(b))_(my)—(U^(c)—Ar^(c))_(mz)]_(m)—*  (VII-10) wherein Ar^(a), Ar^(b), Ar^(c), Ar^(d), Ar^(e), U^(a), U^(b), m1, m2, m3, m4, m5, m6, m7, m, mx, my and mz are as defined above, and U^(c) is as defined above for U^(a) and U^(b).

Such polymers can be alternating or random copolymers. With respect to formulae (VII-4) and (VII-6) it is preferred that in at least one of the repeating units [(Ar^(a))_(m2)—(U^(a))_(m1)—(Ar^(b))_(m4)—(Ar^(c))_(m5)], and—if present—in at least one of the repeating units [(Ar^(a))_(m2)—(Ar^(d))_(m6)—(Ar^(b))_(m4)—(Ar^(c))_(m5)] m1 is at least 1 and m4 is at least 1. With respect to formulae (VII-8) and (VII-9) it is preferred that in at least one of the repeating units [(U^(a))_(m1)—(Ar^(a))_(m2)—(U^(b))_(m3)—(Ar^(b))_(m4)], and—if present—in at least one of the repeating units [(Ar^(d))_(m6)—(Ar^(a))_(m2)—(Ar^(e))_(m7)—(Ar^(b))_(m4)] m1 is at least 1 and m6 is at least 1.

For the present oligomers and polymers the total number m of repeating units is preferably from 2 to 10000. For a polymer the total number m of repeating units is preferably at least 10 and most preferably at least 50. For a polymer the total number m of repeating units is preferably at most 2000, more preferably at most 1000 and most preferably at most 500. Any combination of these values is also possible.

The present oligomers and polymers include homopolymers and copolymers, such as for example statistical or random copolymers, alternating copolymers and block copolymers as well as any combination of these.

Particularly preferred are polymers selected from the following groups

-   a) Group 1 consisting of homopolymers of the unit U^(a) or     (Ar^(a)—U^(a)) or (Ar^(a)—U^(a)—Ar^(b)) or (Ar^(a)—U^(a)—Ar^(c)) or     (U^(a)—Ar^(b)—Ar^(c)) or (Ar^(a)—U^(a)—Ar^(b)—Ar^(c)) or     (U^(a)—Ar^(a)—U^(a)), i.e. where all repeating units are identical,     whereby it is noted that a polymer consisting of units     (Ar^(a)—U^(a)) could also be seen as an alternating copolymer     depending on the respective view of the monomeric unit, -   b) Group 2 consisting of random or alternating copolymers formed by     identical units (Ar^(a)—U^(a)—Ar^(b)) or (U^(a)—Ar^(a)—U^(a)) and     identical units (Ar^(c)), -   c) Group 3 consisting of random or alternating copolymers formed by     identical units (Ar^(a)—U^(a)—Ar^(b)) or (U^(a)—Ar^(a)—U^(b)) and     identical units (Ar^(a)), -   d) Group 4 consisting of random or alternating copolymers formed by     identical units (Ar^(a)—U^(a)—Ar^(b)) or (U^(a)—Ar^(a)—U^(b)) and     identical units (Ar^(a)—Ar^(d)—Ar^(b)) or (Ar^(d)—Ar^(a)—Ar^(e)),     wherein in all these groups Ar^(a), Ar^(b), Ar^(c), Ar^(d), Ar^(e),     U^(a) and U^(b) are as defined above and below, in groups 1, 2 and 3     Ar^(a), Ar^(b) and Ar^(c) are different from a single bond, and in     group 4 one of Ar^(a) and Ar^(b) may also denote a single bond.

Preferred polymers of formulae (VII) and (VII-1) to (VII-10) may be those of formula (VIII) R^(e)-chain-R^(f)  (VIII) wherein “chain” denotes a polymer chain of any one of formulae (VII) or (VII-1) to (VII-10), and R^(e) and R^(f) have independently of each other one of the meanings of R⁵ as defined above, or denote, independently of each other, H, F, Br, Cl, I, —CH₂Cl, —CHO, —CR⁰═CR⁰⁰ ₂, —SiR⁰R⁰⁰R⁰⁰⁰, —SiR⁰X″X′″, —SiR⁰R⁰X″, —SnR⁰R⁰⁰R⁰⁰⁰, —BR⁰R⁰⁰, —B(OR⁰)(OR⁰), —B(OH)₂, —O—SO₂—R⁰, —C≡CH, —C≡C—SiR⁰ ₃, —ZnX″ or an endcap group, X″ and X′″ denote halogen, R⁰, R⁰⁰ and R⁰⁰⁰ are as defined earlier, and two of R⁰, R⁰⁰ and R⁰⁰⁰ may also form a ring together with the atom to which they are attached.

Preferred endcap groups R^(e) and R^(f) are H, C₁₋₂₀ alkyl, or optionally substituted C₆₋₁₂ aryl or C₂₋₁₀ heteroaryl, very preferably H, alkyl having from 1 to 10 carbon atoms or phenyl.

In the polymer chains of formulae (VII) and (VII-1) to (VII-10) mx, my and mz denote the mole fraction of units M¹, M² and M³, respectively, and m denotes the degree of polymerisation. These formulae are intended to include block copolymers, random or statistical copolymers and alternating copolymers of M¹, M² and M³, as well as homopolymers of M¹ for the case when mx>0 and my=mz=0.

Further preferred are repeating units, monomers, oligomers and polymers of formulae (IV-a), (IV-b), (V), (V-a-1), (V-a-2), (V-b-1) to (V-b-5), (VI), (VII), (VII-1) to (VII-10) and (VIII) characterised by one or more of the following preferred or alternative aspects provided that such aspects are not mutually exclusive:

-   -   0<my<1 and mz=0;     -   0<my<1 and 0<mz<1;     -   M_(w) is at least 5,000, preferably at least 8,000, more         preferably at least 10,000;     -   M_(w) is at most 300,000, preferably at most 100,000;     -   R^(e) and R^(f) are independently of each other selected from H,         halogen, —CH₂Cl, —CHO, —CH═CH₂—SiR⁰R⁰⁰R⁰⁰⁰, —SnR⁰R⁰⁰R⁰⁰⁰,         —BR⁰R⁰, —B(OR⁰)(OR⁰), —B(OH)₂, C₁-C₂₀-alkyl, C₁-C₂₀-alkoxy,         C₂-C₂₀-alkenyl, C₁-C₂₀-fluoroalkyl and optionally substituted         aryl or heteroaryl, preferably phenyl,     -   R^(c) and R^(d) are independently of each other selected from         the group consisting of Cl, Br, I, O-tosylate, O-triflate,         O-mesylate, O-nonaflate, —SiMe₂F, —SiMeF₂, —O—SO₂Z¹, —B(OZ²)₂,         —CZ³═C(Z⁴)₂, —C≡CH, C≡CSi(Z¹)₃, —ZnX⁰ and —Sn(Z⁴)₃, wherein X⁰         is halogen, and Z¹, Z², Z³ and Z⁴ are selected from the group         consisting of alkyl and aryl, each being optionally substituted,         and two groups Z² may also form a cyclic group.

A particularly preferred polymer is of the following formula (III-a)

with X¹, X², Ar¹, Ar², Ar³, Ar⁴, Ar⁵ and m as defined above.

Another example of a particularly preferred polymer is one of the following formula (III-b)

with Ar⁵, R and m as defined above.

The compounds of the present invention can be synthesized according to or in analogy to methods that are known to the skilled person and are described in the literature. Other methods of preparation can be taken from the examples. For example, the polymers can be suitably prepared by aryl-aryl coupling reactions, such as Yamamoto coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling or Buchwald coupling. Suzuki coupling, Stille coupling and Yamamoto coupling are especially preferred. The monomers which are polymerized to form the repeat units of the polymers can be prepared according to methods which are known to the person skilled in the art.

Thus, the process for preparing the present polymers comprises the step of coupling monomers, therein comprised a monomer comprising the structural unit of formula (I-a) or (I-b), said monomers comprising at least one or alternatively two functional monovalent group selected from the group consisting of Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, —SiMe₂F, —SiMeF₂, —O—SO₂Z¹, —B(OZ²)₂, —CZ³═C(Z³)₂, —C≡CH, —C≡CSi(Z¹)₃, —ZnX⁰ and —Sn(Z⁴)₃, wherein X⁰ is halogen, and Z¹, Z², Z³ and Z⁴ are independently of each other selected from the group consisting of alkyl and aryl, each being optionally substituted, and two groups Z² may also together form a cyclic group.

Preferably the polymers are prepared from monomers of general formula (IV-b) or their preferred subformulae as described above and below.

Another aspect of the invention is a process for preparing a polymer by coupling one or more identical or different monomeric units comprising a structural unit of formula (I-a) or (I-b) or monomers of general formula (IV-a) with each other and/or with one or more co-monomers in a polymerisation reaction, preferably in an aryl-aryl coupling reaction.

Suitable and preferred comonomers may be selected from the following formulae R^(c)—(Ar^(a))_(m2)—Ar^(d)—(Ar^(b))_(m4)—R^(d)  (IX-1) R^(c)—Ar^(a)—R^(d)  (IX-2) R^(c)—Ar^(d)—R^(d)  (IX-3) wherein Ar^(a), Ar^(b), Ar^(d), m2, m4, R^(c) and R^(d) are as defined herein.

Very preferred is a process for preparing a polymer by coupling one or more monomers selected from formula (V-a-1) or (V-a-2) with one or more monomers of formula (IX-1), and optionally with one or more monomers selected from formula (IX-2) and (IX-3), in an aryl-aryl coupling reaction, wherein preferably R^(c) and R^(d) are selected from Cl, Br, I, —B(OZ²)₂ and —Sn(Z⁴)₃.

For example, preferred embodiments of the present invention relate to

a) a process of preparing a polymer by coupling a monomer of formula (IX-1) R^(c)—Ar^(a)—U^(a)—Ar^(b)—R^(d)

-   -   with a monomer of formula (IX-2)         R^(c)—Ar^(a)—R^(d)  (IX-2)     -   in an aryl-aryl coupling reaction; or

b) a process of preparing a polymer by coupling a monomer of formula R^(c)—U^(a)—R_(d)

-   -   with a monomer of formula (IX-1)         R^(c)—Ar^(a)—Ar^(d)—Ar^(b)—R^(d)  (IX-1)     -   in an aryl-aryl coupling reaction; or

c) a process of preparing a polymer by coupling a monomer of formula R^(c)—U^(a)—R^(d)

-   -   with a monomer of formula (IX-3)         R^(c)—Ar^(d)—R^(d)  (IX-3)     -   in an aryl-aryl coupling reaction; or

d) a process of preparing a polymer by coupling a monomer of formula R^(c)—U^(a)—R^(d)

-   -   with a monomer of formula (IX-3)         R^(c)—Ar^(d)—R^(d)  (IX-3)     -   and a monomer of formula (IX-2)         R^(c)—Ar^(a)—R^(d)  (IX-2)     -   in an aryl-aryl coupling reaction; or

e) a process of preparing a polymer by coupling a monomer of formula R^(c)—U^(a)—Ar^(a)—U^(b)—R^(d)

-   -   with a monomer of formula (IX-2)         R^(c)—Ar^(a)—R^(d)  (IX-2)     -   in an aryl-aryl coupling reaction; or

f) a process of preparing a polymer by coupling a monomer of formula R^(c)—U^(a)—R^(d)

-   -   with a monomer of formula (IX-2)         R^(c)—Ar^(a)—R^(d)  (IX-2)     -   and a monomer of formula (IX-3)         R^(c)—Ar^(d)—R^(d)  (IX-3)     -   in an aryl-aryl coupling reaction,         wherein Ar^(a), Ar^(b), Ar^(d), U^(a), U^(b), R^(c) and R^(d)         are as defined herein, with R^(c) and R^(d) preferably selected         from Cl, Br, I, —B(OZ²)₂ and —Sn(Z⁴)₃ as defined in respect to         formulae (VI-a) and (IV-b).

Preferred aryl-aryl coupling and polymerisation methods used in the processes described above and below are Yamamoto coupling, Kumada coupling, Negishi coupling, Suzuki coupling, Stille coupling, Sonogashira coupling, Heck coupling, C—H activation coupling, Ullmann coupling or Buchwald coupling. Especially preferred are Suzuki coupling, Negishi coupling, Stille coupling and Yamamoto coupling. Suzuki coupling is described for example in WO 00/53656 A1. Negishi coupling is described for example in J. Chem. Soc., Chem. Commun., 1977, 683-684. Yamamoto coupling is described for example in T. Yamamoto et al., Prog. Polym. Sci., 1993, 17, 1153-1205, or WO 2004/022626 A1, and Stille coupling is described for example in Z. Bao et al., J. Am. Chem. Soc., 1995, 117, 12426-12435. For example, when using Yamamoto coupling, monomers having two reactive halide groups are preferably used. When using Suzuki coupling, compounds of formula (IV-b) having two reactive boronic acid or boronic acid ester groups or two reactive halide groups are preferably used. When using Stille coupling, monomers having two reactive stannane groups or two reactive halide groups are preferably used. When using Negishi coupling, monomers having two reactive organozinc groups or two reactive halide groups are preferably used.

Preferred catalysts, especially for Suzuki, Negishi or Stille coupling, are selected from Pd(0) complexes or Pd(II) salts. Preferred Pd(0) complexes are those bearing at least one phosphine ligand, for example Pd(Ph₃P)₄. Another preferred phosphine ligand is tris(ortho-tolyl)phosphine, for example Pd(o-Tol₃P)₄. Preferred Pd(II) salts include palladium acetate, for example Pd(OAc)₂. Alternatively the Pd(0) complex can be prepared by mixing a Pd(0) dibenzylideneacetone complex, for example tris(dibenzyl-ideneacetone)dipalladium(0), bis(dibenzylideneacetone)-palladium(0), or Pd(II) salts e.g. palladium acetate, with a phosphine ligand, for example triphenylphosphine, tris(ortho-tolyl)phosphine or tri(tert-butyl)phosphine. Suzuki polymerisation is performed in the presence of a base, for example sodium carbonate, potassium carbonate, lithium hydroxide, potassium phosphate or an organic base such as tetraethylammonium carbonate or tetraethylammonium hydroxide. Yamamoto polymerisation employs a Ni(0) complex, for example bis(1,5-cyclooctadienyl)nickel(0).

Suzuki and Stille polymerisation may be used to prepare homopolymers as well as statistical, alternating and block random copolymers. Statistical or block copolymers can be prepared for example from the above monomers of formula (VI) or its subformulae, wherein one of the reactive groups is halogen and the other reactive group is a boronic acid, boronic acid derivative group or and alkylstannane. The synthesis of statistical, alternating and block copolymers is described in detail for example in WO 03/048225 A2 or WO 2005/014688 A2.

As alternatives to halogens as described above, leaving groups of formula —O—SO₂Z¹ can be used wherein Z¹ is as described above. Particular examples of such leaving groups are tosylate, mesylate and triflate.

Schematic representations of examples for the production of (homo)polymers are shown in Scheme 3.

Blends, Formulations and Devices

The compounds and polymers according to the present invention can also be used in mixtures or polymer blends, for example together with small molecules or monomeric compounds or together with other polymers having charge-transport, semiconducting, electrically conducting, photoconducting and/or light emitting semiconducting properties, or for example with polymers having hole blocking or electron blocking properties for use as interlayers or charge blocking layers in OLED devices. Thus, another aspect of the invention relates to a polymer blend comprising one or more polymers according to the present invention and one or more further polymers having one or more of the above-mentioned properties. These blends can be prepared by conventional methods that are described in prior art and known to the skilled person. Typically the polymers are mixed with each other or dissolved in suitable solvents and the solutions combined.

Another aspect of the invention relates to a formulation comprising one or more small molecules, polymers, mixtures or polymer blends as described above and below and one or more organic solvents.

Preferred solvents are aliphatic hydrocarbons, chlorinated hydrocarbons, aromatic hydrocarbons, ketones, ethers and mixtures thereof. Additional solvents which can be used include 1,2,4-trimethylbenzene, 1,2,3,4-tetra-methyl benzene, pentylbenzene, mesitylene, cumene, cymene, cyclohexylbenzene, diethylbenzene, tetralin, decalin, 2,6-lutidine, 2-fluoro-m-xylene, 3-fluoro-o-xylene, 2-chlorobenzotrifluoride, N,N-dimethylformamide, 2-chloro-6-fluorotoluene, 2-fluoroanisole, anisole, 2,3-dimethylpyrazine, 4-fluoroanisole, 3-fluoroanisole, 3-trifluoro-methylanisole, 2-methylanisole, phenetol, 4-methylanisole, 3-methylanisole, 4-fluoro-3-methylanisole, 2-fluorobenzonitrile, 4-fluoroveratrol, 2,6-dimethylanisole, 3-fluorobenzo-nitrile, 2,5-dimethylanisole, 2,4-dimethylanisole, benzonitrile, 3,5-dimethyl-anisole, N,N-dimethylaniline, ethyl benzoate, 1-fluoro-3,5-dimethoxy-benzene, 1-methylnaphthalene, N-methylpyrrolidinone, 3-fluorobenzo-trifluoride, benzotrifluoride, dioxane, trifluoromethoxy-benzene, 4-fluorobenzotrifluoride, 3-fluoropyridine, toluene, 2-fluoro-toluene, 2-fluorobenzotrifluoride, 3-fluorotoluene, 4-isopropylbiphenyl, phenyl ether, pyridine, 4-fluorotoluene, 2,5-difluorotoluene, 1-chloro-2,4-difluorobenzene, 2-fluoropyridine, 3-chlorofluoro-benzene, 1-chloro-2,5-difluorobenzene, 4-chlorofluorobenzene, chloro-benzene, o-dichlorobenzene, 2-chlorofluorobenzene, p-xylene, m-xylene, o-xylene or mixture of o-, m-, and p-isomers. Solvents with relatively low polarity are generally preferred. For inkjet printing solvents and solvent mixtures with high boiling temperatures are preferred. For spin coating alkylated benzenes like xylene and toluene are preferred.

Examples of especially preferred solvents include, without limitation, dichloromethane, trichloromethane, chlorobenzene, o-dichlorobenzene, tetrahydrofuran, anisole, morpholine, toluene, o-xylene, m-xylene, p-xylene, 1,4-dioxane, acetone, methylethylketone, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate, n-butyl acetate, N,N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetraline, decaline, indane, methyl benzoate, ethyl benzoate, mesitylene and/or mixtures thereof.

The concentration of the compounds or polymers in the solution is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, with % by weight given relative to the total weight of the solution. Optionally, the solution also comprises one or more binders to adjust the rheological properties, as described for example in WO 2005/055248 A1.

After appropriate mixing and ageing, solutions are evaluated as one of the following categories: complete solution, borderline solution or insoluble. The contour line is drawn to outline the solubility parameter-hydrogen bonding limits dividing solubility and insolubility. ‘Complete’ solvents falling within the solubility area can be chosen from literature values such as published in J. D. Crowley et al., Journal of Paint Technology, 1966, 38 (496), 296. Solvent blends may also be used and can be identified as described in Solvents, W. H. Ellis, Federation of Societies for Coatings Technology, p. 9-10, 1986. Such a procedure may lead to a blend of ‘non’-solvents that will dissolve both the polymers of the present invention, although it is desirable to have at least one true solvent in a blend.

The compounds and polymers according to the present invention can also be used in patterned OSC layers in the devices as described above and below. For applications in modern microelectronics it is generally desirable to generate small structures or patterns to reduce cost (more devices/unit area), and power consumption. Patterning of thin layers comprising a polymer according to the present invention can be carried out for example by photolithography, electron beam lithography or laser patterning.

For use as thin layers in electronic or electrooptical devices the compounds, polymers, polymer blends or formulations of the present invention may be deposited by any suitable method. Liquid coating of devices is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. The formulations of the present invention enable the use of a number of liquid coating techniques. Preferred deposition techniques include, without limitation, dip coating, spin coating, ink jet printing, nozzle printing, letter-press printing, screen printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, dry offset lithography printing, flexographic printing, web printing, spray coating, curtain coating, brush coating, slot dye coating or pad printing.

Ink jet printing is particularly preferred when high resolution layers and devices need to be prepared. Selected formulations of the present invention may be applied to prefabricated device substrates by ink jet printing or microdispensing. Preferably industrial piezoelectric print heads such as but not limited to those supplied by Aprion, Hitachi-Koki, InkJet Technology, On Target Technology, Picojet, Spectra, Trident, Xaar may be used to apply the organic semiconductor layer to a substrate. Additionally semi-industrial heads such as those manufactured by Brother, Epson, Konica, Seiko Instruments Toshiba TEC or single nozzle microdispensers such as those produced by Microdrop and Microfab may be used.

In order to be applied by ink jet printing or microdispensing, the compounds or polymers should be first dissolved in a suitable solvent. Solvents must fulfil the requirements stated above and must not have any detrimental effect on the chosen print head. Additionally, solvents should have boiling points>100° C., preferably >140° C. and more preferably >150° C. in order to prevent operability problems caused by the solution drying out inside the print head. Apart from the solvents mentioned above, suitable solvents include substituted and non-substituted xylene derivatives, di-C₁₋₂-alkyl formamide, substituted and non-substituted anisoles and other phenol-ether derivatives, substituted heterocycles such as substituted pyridines, pyrazines, pyrimidines, pyrrolidinones, substituted and non-substituted N,N-di-C₁₋₂-alkylanilines and other fluorinated or chlorinated aromatics.

A preferred solvent for depositing a compound or polymer according to the present invention by ink jet printing comprises a benzene derivative which has a benzene ring substituted by one or more substituents wherein the total number of carbon atoms among the one or more substituents is at least three. For example, the benzene derivative may be substituted with a propyl group or three methyl groups, in either case there being at least three carbon atoms in total. Such a solvent enables an ink jet fluid to be formed comprising the solvent with the compound or polymer, which reduces or prevents clogging of the jets and separation of the components during spraying. The solvent(s) may include those selected from the following list of examples: dodecylbenzene, 1-methyl-4-tert-butylbenzene, terpineol, limonene, isodurene, terpinolene, cymene, diethylbenzene. The solvent may be a solvent mixture, that is a combination of two or more solvents, each solvent preferably having a boiling point>100° C., more preferably >140° C. Such solvent(s) also enhance film formation in the layer deposited and reduce defects in the layer.

The ink jet fluid (that is mixture of solvent, binder and semiconducting compound) preferably has a viscosity at 20° C. of 1-100 mPa·s, more preferably 1-50 mPa·s and most preferably 1-30 mPa·s.

The polymer blends and formulations according to the present invention can additionally comprise one or more further components or additives selected for example from surface-active compounds, lubricating agents, wetting agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents which may be reactive or non-reactive, auxiliaries, colourants, dyes or pigments, sensitizers, stabilizers, nanoparticles or inhibitors.

The compounds and polymers to the present invention are useful as charge transport, semiconducting, electrically conducting, photoconducting or light emitting materials in optical, electrooptical, electronic, electroluminescent or photoluminescent components or devices. In these devices, the polymers of the present invention are typically applied as thin layers or films.

Thus, the present invention also provides the use of the semiconducting compound, polymer, polymers blend, formulation or layer in an electronic device. The formulation may be used as a high mobility semiconducting material in various devices and apparatus. The formulation may be used, for example, in the form of a semiconducting layer or film. Accordingly, in another aspect, the present invention provides a semiconducting layer for use in an electronic device, the layer comprising a compound, polymer blend or formulation according to the invention. The layer or film may be less than about 30 microns. For various electronic device applications, the thickness may be less than about 1 micron thick. The layer may be deposited, for example on a part of an electronic device, by any of the aforementioned solution coating or printing techniques.

The invention additionally provides an electronic device comprising a compound, polymer, polymer blend, formulation or organic semiconducting layer according to the present invention. Preferred devices are OFETs, TFTs, ICs, logic circuits, capacitors, RFID tags, OLEDs, OLETs, OPEDs, OPVs, OPDs, solar cells, laser diodes, photoconductors, photodetectors, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, Schottky diodes, planarising layers, antistatic films, conducting substrates and conducting patterns. Particularly preferred devices are OLEDs.

Especially preferred electronic device are OFETs, OLEDs, OPV and OPD devices, in particular bulk heterojunction (BHJ) OPV devices. In an OFET, for example, the active semiconductor channel between the drain and source may comprise the layer of the invention. As another example, in an OLED device, the charge (hole or electron) injection or transport layer may comprise the layer of the invention.

For use in OPV or OPD devices the polymer according to the present invention is preferably used in a formulation that comprises or contains, more preferably consists essentially of, very preferably exclusively of, a p-type (electron donor) semiconductor and an n-type (electron acceptor) semiconductor. The p-type semiconductor is constituted by a polymer according to the present invention.

The n-type semiconductor can be an inorganic material such as zinc oxide (ZnO_(x)), zinc tin oxide (ZTO), titan oxide (TiO_(x)), molybdenum oxide (MoO_(x)), nickel oxide (NiO_(x)), or cadmium selenide (CdSe), or an organic material such as graphene or a fullerene or a substituted fullerene, for example an indene-C₆₀-fullerene bisaduct like ICBA, or a (6,6)-phenyl-butyric acid methyl ester derivatized methano C₆₀ fullerene, also known as “PCBM-C₆₀” or “C₆₀PCBM”, as disclosed for example in G. Yu, J. Gao, J. C. Hummelen, F. Wudl, A. J. Heeger, Science 1995, Vol. 270, p. 1789 ff and having the structure shown below, or structural analogous compounds with e.g. a C₆₁ fullerene group, a C₇₀ fullerene group, or a C₇₁ fullerene group, or an organic polymer (see for example Coakley, K. M. and McGehee, M. D. Chem. Mater. 2004, 16, 4533).

Preferably the polymer according to the present invention is blended with an n-type semiconductor such as a fullerene or substituted fullerene, like for example PCBM-C₆₀, PCBM-C₇₀, PCBM-C₆₁, PCBM-C₇₁, bis-PCBM-C₆₁, bis-PCBM-C₇₁, ICMA-c₆₀ (1′,4′-Dihydro-naphtho[2′,3′:1,2][5,6]fullerene-C₆₀), ICBA-C₆₀, oQDM-C₆₀(1′,4′-dihydro-naphtho[2′,3′:1,9][5,6]fullerene-C60-lh), bis-oQDM-C₆₀, graphene, or a metal oxide, like for example, ZnO_(x), TiO_(x), ZTO, MoO_(x), NiO_(x), or quantum dots like for example CdSe or CdS, to form the active layer in an OPV or OPD device. The device preferably further comprises a first transparent or semi-transparent electrode on a transparent or semi-transparent substrate on one side of the active layer, and a second metallic or semi-transparent electrode on the other side of the active layer.

Further preferably the OPV or OPD device comprises, between the active layer and the first or second electrode, one or more additional buffer layers acting as hole transporting layer and/or electron blocking layer, which comprise a material such as metal oxide, like for example, ZTO, MoO_(x), NiO_(x), a conjugated polymer electrolyte, like for example PEDOT:PSS, a conjugated polymer, like for example polytriarylamine (PTAA), an organic compound, like for example N,N′-diphenyl-N,N′-bis(1-naphthyl)(1,1′-biphenyl)-4,4′diamine (NPB), N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD), or alternatively as hole blocking layer and/or electron transporting layer, which comprise a material such as metal oxide, like for example, ZnO_(x), TiO_(x), a salt, like for example LiF, NaF, CsF, a conjugated polymer electrolyte, like for example poly[3-(6-trimethylammoniumhexyl)thiophene], poly(9,9-bis(2-ethylhexyl)-fluorene]-b-poly[3-(6-trimethylammoniumhexyl)thiophene], or poly[(9,9-bis(3′-(N,N-dimethyl-amino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] or an organic compound, like for example tris(8-quinolinolato)-aluminium(III) (Alq₃), 4,7-diphenyl-1,10-phenanthroline.

In a blend or mixture of a polymer according to the present invention with a fullerene or modified fullerene, the ratio polymer:fullerene is preferably from 5:1 to 1:5 by weight, more preferably from 1:1 to 1:3 by weight, most preferably 1:1 to 1:2 by weight. A polymeric binder may also be included, from 5 to 95% by weight. Examples of binder include polystyrene (PS), polypropylene (PP) and polymethylmethacrylate (PMMA).

To produce thin layers in BHJ OPV devices the compounds, polymers, polymer blends or formulations of the present invention may be deposited by any suitable method. Liquid coating of devices is more desirable than vacuum deposition techniques. Solution deposition methods are especially preferred. The formulations of the present invention enable the use of a number of liquid coating techniques. Preferred deposition techniques include, without limitation, dip coating, spin coating, ink jet printing, nozzle printing, letter-press printing, screen printing, gravure printing, doctor blade coating, roller printing, reverse-roller printing, offset lithography printing, dry offset lithography printing, flexographic printing, web printing, spray coating, curtain coating, brush coating, slot dye coating or pad printing. For the fabrication of OPV devices and modules area printing method compatible with flexible substrates are preferred, for example slot dye coating, spray coating and the like.

Suitable solutions or formulations containing the blend or mixture of a polymer according to the present invention with a C₆₀ or C₇₀ fullerene or modified fullerene like PCBM must be prepared. In the preparation of formulations, suitable solvent must be selected to ensure full dissolution of both component, p-type and n-type and take into account the boundary conditions (for example rheological properties) introduced by the chosen printing method.

Organic solvent are generally used for this purpose. Typical solvents can be aromatic solvents, halogenated solvents or chlorinated solvents, including chlorinated aromatic solvents. Examples include, but are not limited to chlorobenzene, 1,2-dichlorobenzene, chloroform, 1,2-dichloroethane, dichloromethane, carbon tetrachloride, toluene, cyclohexanone, ethylacetate, tetrahydrofuran, anisole, morpholine, o-xylene, m-xylene, p-xylene, 1,4-dioxane, acetone, methylethylketone, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, ethyl acetate, n-butyl acetate, dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetraline, decaline, indane, methyl benzoate, ethyl benzoate, mesitylene and combinations thereof.

The OPV device can for example be of any type known from the literature (see e.g. Waldauf et al., Appl. Phys. Lett., 2006, 89, 233517).

A first preferred OPV device according to the invention comprises the following layers (in the sequence from bottom to top):

-   -   optionally a substrate,     -   a high work function electrode, preferably comprising a metal         oxide, like for example ITO, serving as anode,     -   an optional conducting polymer layer or hole transport layer,         preferably comprising an organic polymer or polymer blend, for         example of PEDOT:PSS         (poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate), or         TBD         (N,N′-diphenyl-N—N′-bis(3-methylphenyl)-1,1′biphenyl-4,4′-diamine)         or NBD         (N,N′-diphenyl-N—N′-bis(1-napthylphenyl)-1,1′biphenyl-4,4′-diamine),     -   a layer, also referred to as “active layer”, comprising a p-type         and an n-type organic semiconductor, which can exist for example         as a p-type/n-type bilayer or as distinct p-type and n-type         layers, or as blend or p-type and n-type semiconductor, forming         a BHJ,     -   optionally a layer having electron transport properties, for         example comprising LiF,     -   a low work function electrode, preferably comprising a metal         like for example aluminum, serving as cathode,         wherein at least one of the electrodes, preferably the anode, is         transparent to visible light, and         wherein the p-type semiconductor is a polymer according to the         present invention.

A second preferred OPV device according to the invention is an inverted OPV device and comprises the following layers (in the sequence from bottom to top):

-   -   optionally a substrate,     -   a high work function metal or metal oxide electrode, comprising         for example ITO, serving as cathode,     -   a layer having hole blocking properties, preferably comprising a         metal oxide like TiO_(x) or Zn_(x),     -   an active layer comprising a p-type and an n-type organic         semiconductor, situated between the electrodes, which can exist         for example as a p-type/n-type bilayer or as distinct p-type and         n-type layers, or as blend or p-type and n-type semiconductor,         forming a BHJ,     -   an optional conducting polymer layer or hole transport layer,         preferably comprising an organic polymer or polymer blend, for         example of PEDOT:PSS or TBD or NBD,     -   an electrode comprising a high work function metal like for         example silver, serving as anode,         wherein at least one of the electrodes, preferably the cathode,         is transparent to visible light, and         wherein the p-type semiconductor is a polymer according to the         present invention.

In the OPV devices of the present invention the p-type and n-type semiconductor materials are preferably selected from the materials, like the polymer/fullerene systems, as described above

When the active layer is deposited on the substrate, it forms a BHJ that phase separates at nanoscale level. For discussion on nanoscale phase separation see Dennler et al, Proceedings of the IEEE, 2005, 93 (8), 1429 or Hoppe et al, Adv. Func. Mater, 2004, 14(10), 1005. An optional annealing step may be then necessary to optimize blend morphology and consequently OPV device performance.

Another method to optimize device performance is to prepare formulations for the fabrication of OPV(BHJ) devices that may include high boiling point additives to promote phase separation in the right way. 1,8-Octanedithiol, 1,8-diiodooctane, nitrobenzene, chloronaphthalene, and other additives have been used to obtain high-efficiency solar cells. Examples are disclosed in J. Peet, et al, Nat. Mater., 2007, 6, 497 or Frechet et al. J. Am. Chem. Soc., 2010, 132, 7595-7597.

The compounds, polymers, formulations and layers of the present invention are also suitable for use in an OFET as the semiconducting channel. Accordingly, the invention also provides an OFET comprising a gate electrode, an insulating (or gate insulator) layer, a source electrode, a drain electrode and an organic semiconducting channel connecting the source and drain electrodes, wherein the organic semiconducting channel comprises a compound, polymer, polymer blend, formulation or organic semiconducting layer according to the present invention. Other features of the OFET are well known to those skilled in the art.

OFETs where an OSC material is arranged as a thin film between a gate dielectric and a drain and a source electrode, are generally known, and are described for example in U.S. Pat. No. 5,892,244, U.S. Pat. No. 5,998,804, U.S. Pat. No. 6,723,394 and in the references cited in the background section. Due to the advantages, like low cost production using the solubility properties of the compounds according to the invention and thus the processability of large surfaces, preferred applications of these FETs are such as integrated circuitry, TFT displays and security applications.

The gate, source and drain electrodes and the insulating and semiconducting layer in the OFET device may be arranged in any sequence, provided that the source and drain electrode are separated from the gate electrode by the insulating layer, the gate electrode and the semiconductor layer both contact the insulating layer, and the source electrode and the drain electrode both contact the semiconducting layer.

An OFET device according to the present invention preferably comprises:

-   -   a source electrode,     -   a drain electrode,     -   a gate electrode,     -   a semiconducting layer,     -   one or more gate insulator layers, and     -   optionally a substrate,         wherein the semiconductor layer preferably comprises a compound,         polymer, polymer blend or formulation as described above and         below.

The OFET device can be a top gate device or a bottom gate device. Suitable structures and manufacturing methods of an OFET device are known to the skilled in the art and are described in the literature, for example in US 2007/0102696 A1.

The gate insulator layer preferably comprises a fluoropolymer, like e.g. the commercially available Cytop 809M® or Cytop 107M® (from Asahi Glass). Preferably the gate insulator layer is deposited, e.g. by spin-coating, doctor blading, wire bar coating, spray or dip coating or other known methods, from a formulation comprising an insulator material and one or more solvents with one or more fluoro atoms (fluorosolvents), preferably a perfluorosolvent. A suitable perfluorosolvent is e.g. FC75® (available from Acros, catalogue number 12380). Other suitable fluoropolymers and fluorosolvents are known in prior art, like for example the perfluoropolymers Teflon AF® 1600 or 2400 (from DuPont) or Fluoropel® (from Cytonix) or the perfluorosolvent FC 43® (Acros, No. 12377). Especially preferred are organic dielectric materials having a low permittivity (or dielectric contant) from 1.0 to 5.0, very preferably from 1.8 to 4.0 (“low k materials”), as disclosed for example in US 2007/0102696 A1 or U.S. Pat. No. 7,095,044.

In security applications, OFETs and other devices with semiconducting materials according to the present invention, like transistors or diodes, can be used for RFID tags or security markings to authenticate and prevent counterfeiting of documents of value like banknotes, credit cards or ID cards, national ID documents, licenses or any product with monetry value, like stamps, tickets, shares, cheques etc.

Alternatively, the materials according to the invention can be used in OLEDs, e.g. as the active display material in a flat panel display applications, or as backlight of a flat panel display like e.g. a liquid crystal display. Common OLEDs are realized using multilayer structures. An emission layer is generally sandwiched between one or more electron-transport and/or hole-transport layers. By applying an electric voltage electrons and holes as charge carriers move towards the emission layer where their recombination leads to the excitation and hence luminescence of the lumophor units contained in the emission layer. The inventive compounds, materials and films may be employed in one or more of the charge transport layers and/or in the emission layer, corresponding to their electrical and/or optical properties. Furthermore their use within the emission layer is especially advantageous, if the compounds, materials and films according to the invention show electroluminescent properties themselves or comprise electroluminescent groups or compounds. The selection, characterization as well as the processing of suitable monomeric, oligomeric and polymeric compounds or materials for the use in OLEDs is generally known by a person skilled in the art, see, e.g., Müller et al, Synth. Metals, 2000, 111-112, 31-34, Alcala, J. Appl. Phys., 2000, 88, 7124-7128 and the literature cited therein.

According to another use, the materials according to this invention, especially those showing photoluminescent properties, may be employed as materials of light sources, e.g. in display devices, as described in EP 0 889 350 A1 or by C. Weder et al., Science, 1998, 279, 835-837.

A further aspect of the invention relates to both the oxidised and reduced form of the compounds according to this invention. Either loss or gain of electrons results in formation of a highly delocalised ionic form, which is of high conductivity. This can occur on exposure to common dopants. Suitable dopants and methods of doping are known to those skilled in the art, e.g. from EP 0 528 662, U.S. Pat. No. 5,198,153 or WO 96/21659.

The doping process typically implies treatment of the semiconductor material with an oxidating or reducing agent in a redox reaction to form delocalised ionic centres in the material, with the corresponding counterions derived from the applied dopants. Suitable doping methods comprise for example exposure to a doping vapor in the atmospheric pressure or at a reduced pressure, electrochemical doping in a solution containing a dopant, bringing a dopant into contact with the semiconductor material to be thermally diffused, and ion-implantantion of the dopant into the semiconductor material.

When electrons are used as carriers, suitable dopants are for example halogens (e.g., I₂, C₂, Br₂, IC, ICl₃, IBr and IF), Lewis acids (e.g., PF₅, AsF₅, SbF₅, BF₃, BCl₃, SbCl₅, BBr₃ and SO₃), protonic acids, organic acids, or amino acids (e.g., HF, HCl, HNO₃, H₂SO₄, HClO₄, FSO₃H and ClSO₃H), transition metal compounds (e.g., FeCl₃, FeOCl, Fe(ClO₄)₃, Fe(4-CH₃C₆H₄SO₃)₃, TiCl₄, ZrCl₄, HfCl₄, NbF₅, NbCl₅, TaCl₅, MoF₅, MoCl₅, WF₅, WCl₆, UF₆ and LnCl₃ (wherein Ln is a lanthanoid), anions (e.g., Cl⁻, Br⁻, I⁻, I₃ ⁻, HSO₄ ⁻, SO₄ ²⁻, NO₃ ⁻, CO₄ ⁻, BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, FeCl₄ ⁻, Fe(CN)₆ ³⁻, and anions of various sulfonic acids, such as aryl-SO₃ ⁻). When holes are used as carriers, examples of dopants are cations (e.g., H⁺, Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺), alkali metals (e.g., Li, Na, K, Rb, and Cs), alkaline-earth metals (e.g., Ca, Sr, and Ba), O₂, XeOF₄, (NO₂ ⁺) (SbF₆ ⁻), (NO₂ ⁺) (SbCl₆ ⁻), (NO₂ ⁺) (BF₄ ⁻), AgClO₄, H₂IrCl₆, La(NO₃)₃.6H₂O, FSO₂OOSO₂F, Eu, acetylcholine, R₄N⁺, (R is an alkyl group), R₄P⁺ (R is an alkyl group), R₆As⁺ (R is an alkyl group), and R₃S⁺ (R is an alkyl group).

The conducting form of the compounds of the present invention can be used as an organic “metal” in applications including, but not limited to, charge injection layers and ITO planarising layers in OLED applications, films for flat panel displays and touch screens, antistatic films, printed conductive substrates, patterns or tracts in electronic applications such as printed circuit boards and condensers.

The compounds and formulations according to the present invention may also be suitable for use in organic plasmon-emitting diodes (OPEDs), as described for example in Koller et al., Nat. Photonics, 2008, 2, 684.

According to another use, the materials according to the present invention can be used alone or together with other materials in or as alignment layers in LCD or OLED devices, as described for example in US 2003/0021913. The use of charge transport compounds according to the present invention can increase the electrical conductivity of the alignment layer. When used in an LCD, this increased electrical conductivity can reduce adverse residual dc effects in the switchable LCD cell and suppress image sticking or, for example in ferroelectric LCDs, reduce the residual charge produced by the switching of the spontaneous polarisation charge of the ferroelectric LCs. When used in an OLED device comprising a light emitting material provided onto the alignment layer, this increased electrical conductivity can enhance the electroluminescence of the light emitting material. The compounds or materials according to the present invention having mesogenic or liquid crystalline properties can form oriented anisotropic films as described above, which are especially useful as alignment layers to induce or enhance alignment in a liquid crystal medium provided onto said anisotropic film. The materials according to the present invention may also be combined with photoisomerisable compounds and/or chromophores for use in or as photoalignment layers, as described in US 2003/0021913 A1.

According to another use the materials according to the present invention, especially their water-soluble derivatives (for example with polar or ionic side groups) or ionically doped forms, can be employed as chemical sensors or materials for detecting and discriminating DNA sequences. Such uses are described for example in L. Chen, D. W. McBranch, H. Wang, R. Helgeson, F. Wudl and D. G. Whitten, Proc. Natl. Acad. Sci. U.S.A., 1999, 96, 12287; D. Wang, X. Gong, P. S. Heeger, F. Rininsland, G. C. Bazan and A. J. Heeger, Proc. Natl. Acad. Sci. U.S.A., 2002, 99, 49; N. DiCesare, M. R. Pinot, K. S. Schanze and J. R. Lakowicz, Langmuir, 2002, 18, 7785; D. T. McQuade, A. E. Pullen, T. M. Swager, Chem. Rev., 2000, 100, 2537.

Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, mean “including but not limited to”, and are not intended to (and do not) exclude other components.

It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

Above and below, unless stated otherwise percentages are percent by weight and temperatures are given in degrees Celsius. The values of the dielectric constant E (“permittivity”) refer to values taken at 20° C. and 1,000 Hz.

EXAMPLES

The following non-limiting examples further illustrate the advantages of the present invention.

Example 1

Compound 1

To a mixture of 1-bromo-4-hexacybenzene (24.7 g, 65 mmol) in anhydrous tetrahydrofuran (150 cm³) at −50° C. was added n-butyllithium (25.9 cm³, 2.5 M in hexane, 65 mmol) over 20 minutes. After addition, the solution was stirred at −50° C. for 1 hour. 2,5-Di-thiophen-2-yl-terephthalic acid diethyl ester (5.0 g, 13 mmol) was then added as a solid and the reaction allowed to stir and warm in the cooling-bath over 17 hours. Water (200 cm³) was added. The product was extracted with ether (2×200 cm³) and the combined organics dried over anhydrous magnesium sulfate, filtered and the solvent removed in vacuo. The residue was taken up in dichloromethane (60 cm³) and p-toluenesulfonic acid (0.50 g, 2.6 mmol) added. The mixture was stirred at 23° C. for 2 hours. Methanol (100 cm³) was added and the solid collected by filtration. The crude was passed through a plug of silica (cyclohexane) and after concentration in vacuo, the residue was taken up in dichloromethane (50 cm³) and methanol (200 cm³) added. The precipitate was collected by filtration and washed with methanol (100 cm³) to give compound 1 (11.2 g, 59%) as a white solid.

¹H-NMR (300 MHz, CDCl₃) 0.86-0.94 (12H, m), 1.19-1.40 (104H, m), 1.53-1.65 (8H, m), 2.56 (8H, t, J 7.8), 7.01 (2H, d, J 5.0), 7.03-7.09 (8H, m), 7.13-7.20 (8H, m), 7.25 (2H, d, J 5.0), 7.44 (2H, s).

Compound 2

To a solution of compound 1 (5.0 g, 3.4 mmol) in chloroform (300 cm³) and acetic acid (50 cm³) was added N-bromosuccinimide (1.3 g, 7.2 mmol) and the mixture stirred at 23° C. for 3 hours. The mixture was warmed to 40° C. for 10 minutes to dissolve the precipitate and the mixture was stirred again at 23° C. for 1 hour. The mixture was concentrated in vacuo, methanol (300 cm³) added and the precipitate collected by filtration. The residue was passed through a plug of silica (cyclohexanes) and the solution was concentrated in vacuo. Methanol (200 cm³) was added and the solid collected by filtration to give compound 2 (5.2 g, 94%) as a white solid, 5.2 g.

¹H-NMR (300 MHz, CDCl₃) 0.86-0.94 (12H, m), 1.21-1.39 (104H, m), 1.44-1.65 (8H, m), 2.57 (8H, t, J 7.8), 7.00 (2H, s), 7.05-7.15 (16H, m), 7.34 (2H, s).

Polymer 1

Nitrogen gas was bubbled through a mixture of compound 2 (500.0 mg, 0.307 mmol), 2,5-thieno[3,2-b]thiophene (143.2 mg, 0.307 mmol), tri-o-tolyl-phosphine (14 mg, 0.05 mmol), tris(dibenzylideneacetone)dipalladium(0) (8.7 mg, 0.01 mmol), anhydrous toluene (10 cm³) and anhydrous N,N-dimethylformamide (2 cm³) for 30 minutes. The reaction mixture was then heated in a pre-heated oil bath at 110° C. for 9 minutes. Bromobenzene (0.02 cm³) was added and the mixture heated at 110° C. for 5 minutes before addition of tributyl-phenyl-stannane (0.08 cm³). The mixture was heated at 110° C. for 5 minutes. The mixture was allowed to cool slightly and poured into stirred methanol (100 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 80-100 petroleum ether and chloroform. The chloroform extract was poured into methanol (400 cm³) and the polymer precipitate collected by filtration to give polymer 2 (440 mg, 89%) as a red solid.

GPC (chlorobenzene, 50° C.) M_(n)=152,000 g/mol, M_(w)=597,000 g/mol.

Example 2

Compound 3

To a mixture of compound 2 (5.0 g, 3.1 mmol) and anhydrous tetrahydrofuran (180 cm³) at −78° C. was added n-butyllithium (4.0 cm³, 2.5 M in hexane, 10 mmol) dropwise over 10 minutes. The reaction mixture was stirred at −78° C. for 80 minutes. Trimethyltin chloride (10.8 cm³, 1.0 M in tetrahydrofuran, 10.8 mmol) was then added and the mixture stirred at −78° C. for 10 minutes and at 23° C. for 90 minutes. The volatiles were removed in vacuo and 40-60 petrol (100 cm³) added. The mixture was filtered and the solvent removed in vacuo. The residue was triturated in acetone (100 cm³) and the solid collected and washed with acetone (100 cm³), methanol (100 cm³), water (100 cm³), methanol (100 cm³) and acetone (100 cm³) sequentially. The solid was then recrystallised from hexane to give compound 3 (5.03 g, 91%) as a white powdery solid.

¹H-NMR (300 MHz, CDCl₃) 0.22-0.33 (18H, m), 0.84-0.91 (12H, m), 1.20-1.36 (104H, m), 1.53-1.62 (8H, m), 2.54 (8H, t, J 7.8), 7.01 (2H, s), 7.00-7.06 (8H, m), 7.12-7.17 (8H, m), 7.38 (2H, s).

Polymer 2

Nitrogen gas was bubbled through a mixture of compound 3 (584.9 mg, 0.326 mmol), 4,7-dibromo-benzo[1,2,5]thiadiazole (95.8 mg, 0.326 mmol), tri-o-tolyl-phosphine (6.1 mg, 0.02 mmol), tris(dibenzylideneacetone)dipalladium(0) (3.6 mg, 0.005 mmol), anhydrous toluene (7 cm³) and anhydrous N,N-dimethylformamide (1 cm³) for 30 minutes. The reaction mixture was then heated in a pre-heated oil bath at 120° C. for 17 hours. Tributyl-phenyl-stannane (0.02 cm³) was added and the mixture heated at 120° C. for 5 minutes before addition of bromobenzene (0.02 cm³). The mixture was heated at 110° C. for 5 minutes. The mixture was allowed to cool slightly and poured into stirred methanol (100 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 40-60 petrol, 80-100 petrol and cyclohexane. The cyclohexane extract was concentrated in vacuo and the residue taken up in chloroform (40 cm³). The solution was poured into methanol (400 cm³) and the polymer precipitate collected by filtration to give polymer 2 (450 mg, 86%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=91,000 g/mol, M_(w)=210,000 g/mol.

Example 3

Polymer 3

Nitrogen gas was bubbled through a mixture of compound 3 (417.1 mg, 0.233 mmol), 4,7-dibromo-5,6-difluoro-benzo[1,2,5]thiadiazole (76.7 mg, 0.233 mmol), tri-o-tolyl-phosphine (6.1 mg, 0.02 mmol), tris(dibenzylideneacetone)di-palladium(0) (3.6 mg, 0.005 mmol), anhydrous toluene (5 cm³) and anhydrous N,N-dimethylformamide (0.7 cm³) for 30 minutes. The reaction mixture was then heated in a pre-heated oil bath at 120° C. for 4 hours. Tributyl-phenyl-stannane (0.02 cm³) was added and the mixture heated at 120° C. for 5 minutes before addition of bromobenzene (0.02 cm³). The mixture was heated at 110° C. for 5 minutes. The mixture was then allowed to cool slightly and poured into stirred methanol (100 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 80-100 petrol and chloroform. The chloroform extract was poured into methanol (400 cm³) and the polymer precipitate collected by filtration to give polymer 3 (360 mg, 95%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=54,000 g/mol, M_(w)=128,000 g/mol.

Example 4

Polymer 4

Nitrogen gas was bubbled through a mixture of compound 3 (514.9 mg, 0.287 mmol), 5,10-dibromo-2,7-dithia-1,3,6,8-tetraaza-dicyclopenta[a,f]naphthalene (115.5 mg, 0.287 mmol), tri-o-tolyl-phosphine (7.0 mg, 0.02 mmol), tris(dibenzylideneacetone)di-palladium(0) (4.0 mg, 0.006 mmol), anhydrous toluene (5 cm³) and anhydrous N,N-dimethylformamide (1 cm³) for 60 minutes. The reaction mixture was then heated in a pre-heated oil bath at 110° C. for 16 hours. Tributyl-phenyl-stannane (0.1 cm³) was added and the mixture heated at 110° C. for 60 minutes before addition of bromobenzene (0.1 cm³). The mixture was heated at 110° C. for 60 minutes. The mixture was then allowed to cool to 23° C. and poured into stirred methanol (200 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 40-60 petrol and chloroform. The chloroform extract was concentrated in vacuo, poured into methanol (200 cm³) and the polymer precipitate collected by filtration to give polymer 4 (380 mg, 78%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=9,700 g/mol, M_(w)=15,400 g/mol.

Example 5

Polymer 5

Nitrogen gas was bubbled through a mixture of compound 3 (305.0 mg, 0.170 mmol), 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (50.1 mg, 0.170 mmol), tri-o-tolyl-phosphine (17.1 mg, 0.056 mmol) and anhydrous toluene (5.4 cm³). Tris(dibenzylideneacetone)di-palladium(0) (10.8 mg, 0.015 mmol) was added and the reaction mixture then heated in a pre-heated oil bath at 110° C. for 2 hours. Bromobenzene (0.004 cm³) was added and the mixture heated at 110° C. for 30 minutes before addition of tributyl-phenyl-stannane (0.02 cm³). The mixture was heated at 110° C. for 60 minutes. The mixture was then allowed to cool slightly and poured into stirred methanol (300 cm³) and the polymer precipitate collected by filtration and washed with acetone (50 cm³). The crude polymer was subjected to sequential soxhlet extraction with acetone, 40-60 petrol, 80-100 petrol, cyclohexane and chloroform. The chloroform extract was poured into methanol (500 cm³) and the polymer precipitate collected by filtration to give polymer 5 (232 mg, 85%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=58,200 g/mol, M_(w)=119,000 g/mol.

Example 6

Polymer 6

Nitrogen gas was bubbled through a mixture of compound 3 (584.8 mg, 0.326 mmol), 5,5′-dibromo-3,3′-difluoro-[2,2′]bithiophenyl (117.3 mg, 0.326 mmol), tri-o-tolyl-phosphine (6.1 mg, 0.02 mmol), tris(dibenzylideneacetone)di-palladium(0) (3.6 mg, 0.005 mmol), anhydrous toluene (7 cm³) and anhydrous N,N-dimethylformamide (1 cm³). The reaction mixture was then heated in a pre-heated oil bath at 110° C. for 17 hours. Tributyl-phenyl-stannane (0.02 cm³) was added and the mixture heated at 110° C. for 5 minutes before addition of bromobenzene (0.02 cm³). The mixture was heated at 110° C. for 5 minutes. The mixture was then allowed to cool slightly and poured into stirred methanol (100 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 40-60 petrol, 80-100 petrol, cyclohexane and chloroform. The chloroform extract was poured into methanol (500 cm³) and the polymer precipitate collected by filtration to give polymer 6 (460 mg, 85%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=94,000 g/mol, M_(w)=223,000 g/mol.

Example 7

Polymer 7

Nitrogen gas was bubbled through a mixture of compound 3 (172.6 mg, 0.096 mmol), 4-(2-Ethyl-hexyl)-2,6-bis-trimethylstannanyl-4H-dithieno[3,2-b;2′,3′-d]pyrrole (59.6 mg, 0.096 mmol), 4,8-bis-(5-bromo-thiophen-2-yl)-6-(4-hexyl-dodecyl)-[1,2,5]thiadiazolo[3,4-e]isoindole-5,7-dione (150.0 mg, 0.192 mmol), tri-o-tolyl-phosphine (19.3 mg, 0.06 mmol), anhydrous toluene (7 cm³) and anhydrous N,N-dimethylformamide (1 cm³). Tris(dibenzylideneacetone)di-palladium(0) (12.2 mg, 0.02 mmol) was added and the reaction mixture then heated in a pre-heated oil bath at 110° C. for 2 hours. Bromobenzene (0.02 cm³) was added and the mixture heated at 110° C. for 5 minutes before addition of tributyl-phenyl-stannane (0.08 cm³). The mixture was heated at 110° C. for 5 minutes. The mixture was then allowed to cool slightly and poured into stirred methanol (100 cm³) and the polymer precipitate collected by filtration. The crude polymer was subjected to sequential soxhlet extraction with acetone, 40-60 petrol, 80-100 petrol and chloroform. The chloroform extract was poured into methanol (500 cm³) and the polymer precipitate collected by filtration to give polymer 7 (317 mg, 55%) as a black solid.

GPC (chlorobenzene, 50° C.) M_(n)=72,400 g/mol, M_(w)=285,900 g/mol.

Example 8—Transistor Fabrication and Measurement

Top-gate thin-film organic field-effect transistors (OFETs) were fabricated on glass substrates with photolithographically defined Au source-drain electrodes. A 7 mg/cm³ solution of the organic semiconductor in dichlorobenzene was spin-coated on top (an optional annealing of the film is carried out at 100° C., 150° C. or 200° C. for between 1 and 5 minutes) followed by a spin-coated fluoropolymer dielectric material (Lisicon® D139 from Merck, Germany). Finally a photolithographically defined Au gate electrode was deposited. The electrical characterization of the transistor devices was carried out in ambient air atmosphere using computer controlled Agilent 4155C Semiconductor Parameter Analyser. Charge carrier mobility in the saturation regime (μ_(sat)) was calculated for the compound. Field-effect mobility was calculated in the saturation regime (V_(d)>(V_(g)—V₀)) using equation (1):

$\begin{matrix} {\left( \frac{{dI}_{\mathbb{d}}^{sat}}{{dV}_{g}} \right)_{V_{d}} = {\frac{{WC}_{i}}{L}{\mu^{sat}\left( {V_{g} - V_{0}} \right)}}} & (1) \end{matrix}$ where W is the channel width, L the channel length, C_(i) the capacitance of insulating layer, V_(g) the gate voltage, V₀ the turn-on voltage, and μ_(sat) is the charge carrier mobility in the saturation regime. Turn-on voltage (V₀) was determined as the onset of source-drain current.

The mobilities (μ_(sat)) for polymers 1, 2, 3, 4, 5 and 6 in top-gate OFETs are summarized in Table 1.

TABLE 1 Polymer μ_(sat) [cm²/Vs] 1 0.12 2 1.21 3 0.10 4 0.05 5 0.20 6 0.02 

The invention claimed is:
 1. A compound comprising at least one unit M selected from the group consisting of formula (I-a) and formula (I-b)

wherein * denotes a linkage to an adjacent unit or group, X¹ and X² are independently of each other S or Se; Ar¹, Ar², Ar³ and Ar⁴ are independently of each other aryl comprising at least one substituent group R, R is an organyl or organoheteryl comprising from 13 to 19 carbon atoms; a is 0 or an integer from 1 to 10; and Ar⁵ is at each occurrence independently selected from the group consisting of aryl, substituted aryl, heteroaryl and substituted heteroaryl having up to 30 aromatic ring atoms.
 2. The compound according to claim 1, wherein Ar¹, Ar², Ar³ and Ar⁴ are independently of each other selected from the group consisting of formulae (F1) to (F9)

wherein * denotes a linkage of Ar¹, Ar², Ar³ or Ar⁴ to the remaining part of (I-a) or formula (I-b), R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ are independently of each other selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —SF₅, —SiR⁰R⁰⁰R⁰⁰⁰, substituted hydrocarbyl having from 1 to 40 carbon atoms, unsubstituted hydrocarbyl having from 1 to 40 carbon atoms, substituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te and Ge, and unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O, S, P, Si, Se, As, Te and Ge, provided that at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R, R is an organyl or organoheteryl comprising from 13 to 19 carbon atoms; R⁰, R⁰⁰ and R⁰⁰⁰ are at each occurrence independently of each other H, F or C₁₋₄₀ organyl or organoheteryl, optionally substituted; and X⁰ is halogen.
 3. The compound according to claim 1, wherein Ar¹, Ar², Ar³ and Ar⁴ are independently of each other phenyl comprising at least one substituent group R.
 4. The compound according to claim 1, wherein Ar¹, Ar², Ar³ and Ar⁴ are independently of each other

* denotes a linkage of Ar¹, Ar², Ar³ or Ar⁴ to the remaining part of (I-a) or formula (I-b).
 5. The compound according to claim 1, wherein R is alkyl having from 13 to 19 carbon atoms.
 6. The compound according to claim 1, wherein X¹ and X² are S.
 7. The compound according to claim 1, wherein a is not 0 and Ar⁵ is at each occurrence independently arylene or heteroarylene having electron donor properties or arylene or heteroarylene having electron acceptor properties.
 8. The compound according to claim 1, which comprises at least two units M.
 9. The compound according to claim 1, which is an oligomer or a polymer.
 10. The compound according to claim 1, wherein a is
 1. 11. The compound according to claim 1, which is of formula (III-a)

wherein m is at least 10, and *, Ar¹, Ar², Ar³, Ar⁴, Ar⁵, X¹ and X² are as defined for the compound of formula (I-a) or (I-b).
 12. The compound according to claim 1, which of formula (III-b)

wherein m is at least 10, and *, Ar⁵ and R are as defined for the compound of formula (I-a) or (I-b).
 13. A mixture or a blend comprising one or more compounds of claim 1 and one or more compounds or polymers selected from the group consisting of binders and compounds and polymers having semiconducting, charge transport, hole transport, electron transport, hole blocking, electron blocking, electrically conducting, photoconducting or light emitting properties.
 14. A formulation comprising the compound of claim 1 and an organic solvent.
 15. An optical, electrooptical, electronic, electroluminescent or photoluminescent component or device comprising a compound of claim
 1. 16. A charge transport, semiconducting, electrically conducting, photoconducting or light emitting material comprising the compound of claim
 1. 17. A component or device comprising the compound of claim 1, said component or device being selected from the group consisting of organic field effect transistors (OFET), thin film transistors (TFT), integrated circuits (IC), logic circuits, capacitors, radio frequency identification (RFID) tags, organic light emitting diodes (OLED), organic light emitting transistors (OLET), flat panel displays, backlights of displays, organic photovoltaic devices (OPV), organic solar cells (O-SC), photodiodes, laser diodes, photoconductors, organic photodetectors (OPD), electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, charge injection layers, charge transport layers or interlayers in polymer light emitting diodes (PLEDs), Schottky diodes, planarising layers, antistatic films, polymer electrolyte membranes (PEM), conducting substrates, conducting patterns, electrode materials in batteries, alignment layers, biosensors, biochips, security markings, security devices, and components and devices for detecting and discriminating DNA sequences.
 18. A component or device according to claim 17, said component or device being selected from the group consisting of organic field effect transistors (OFET), thin film transistors (TFT), integrated circuitry (IC), radio frequency identification (RFID) tags, organic light emitting devices (OLED), organic light emitting transistors (OLET) and backlights of displays.
 19. The compound according to claim 1, wherein R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ are independently of each other selected from the group consisting of H, F, Br, Cl, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(O)NR⁰R⁰⁰, —C(O)X⁰, —C(O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —OR⁰, —NO₂, —SF₅, —SiR⁰R⁰⁰,R⁰⁰⁰, substituted hydrocarbyl having from 1 to 40 carbon atoms, unsubstituted hydrocarbyl having from 1 to 40 carbon atoms, substituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O and S, and unsubstituted hydrocarbyl having from 1 to 40 carbon atoms comprising one or more heteroatoms selected from the group consisting of N, O and S, provided that at least one of R²¹, R²², R²³, R²⁴, R²⁵, R²⁶, R²⁷, R²⁸ and R²⁹ is R, R is an organyl or organoheteryl comprising from 13 to 19 carbon atoms.
 20. A compound comprising at least one unit M selected from the group consisting of formula (I-a) and formula (I-b)

wherein * denotes a linkage to an adjacent unit or group, X¹ and X² are independently of each other S or Se; Ar¹, Ar², Ar³ and Ar⁴ are independently of each other aryl comprising at least one substituent group R, R is a linear alkyl group comprising from 13 to 19 carbon atoms; a is 0 or an integer from 1 to 10; and Ar⁵ is at each occurrence independently selected from the group consisting of aryl, substituted aryl, heteroaryl and substituted heteroaryl having up to 30 aromatic ring atoms. 